On 2024-04-18 14:52, Sergei Trofimovich wrote:
> $ clang simple.c -o simple && echo 42 | ./simple
> 1: ino=3009428657538693161
> 2: ino=3009428657538693161
> 3: ino=1568241705
> 
> Note how stat() and fstat() don't agree on inode.
> 
> Apparently it's documented in
> https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/fstat.2.html
> as
> 
>    BUGS
>       Applying fstat to a socket (and thus to a pipe) returns a zero'd buffer,
>       except for the blocksize field, and a unique device and inode number.

The BUGS note simply means that a pipe has a unique inode number, which 
is what we want. So that's not indicating any problem.


Oh, I see the problem now.  For a socket or pipe, macOS fstat returns 
the full 64-bit inode number, whereas macOS stat returns only the low 
order 32 bits.  In your example, 3009428657538693161 % (2**32) == 
1568241705.

This is a kernel bug in macOS. Can you report it or otherwise arrange to 
have the kernel bug fixed? I expect that you have better connections 
with Apple than I do. A proposed patch (relative to xnu-10063.101.15) is 
attached; I have not tested it as I don't use macOS. Thanks.

Also, I am documenting this macOS bug in Gnulib by installing the second 
attached patch to Gnulib, and am cc'ing this email to bug-gnulib.